The present disclosure generally relates to dialysis systems. More specifically, the present disclosure relates to therapy prediction and optimization systems and methods for hemodialysis, especially home hemodialysis (“HHD”).
Hemodialysis (“HD”) in general uses diffusion to remove waste products from a patient's blood. A diffusive gradient that occurs across the semi-permeable dialysis membrane between the blood and an electrolyte solution called dialysate causes diffusion. Hemofiltration (“HF”) is an alternative renal replacement therapy that relies on a convective transport of toxins from the patient's blood. This therapy is accomplished by adding substitution or replacement fluid to the extracorporeal circuit during treatment (typically ten to ninety liters of such fluid). That substitution fluid and the fluid accumulated by the patient in between treatments is ultrafiltered over the course of the HF treatment, providing a convective transport mechanism that is particularly beneficial in removing middle and large molecules (in hemodialysis there is a small amount of waste removed along with the fluid gained between dialysis sessions, however, the solute drag from the removal of that ultrafiltrate is not enough to provide convective clearance).
Hemodiafiltration (“HDF”) is a treatment modality that combines convective and diffusive clearances. HDF uses dialysate to flow through a dialyzer, similar to standard hemodialysis, providing diffusive clearance. In addition, substitution solution is provided directly to the extracorporeal circuit, providing convective clearance.
Home hemodialysis (“HHD”) has to date had limited acceptance even though the clinical outcomes of this modality are more attractive than conventional hemodialysis. There are benefits to daily hemodialysis treatments versus bi- or tri-weekly visits to a treatment center. In certain instances, a patient receiving more frequent treatments removes more toxins and waste products than a patient receiving less frequent but perhaps longer treatments.
In any of the blood therapy treatments listed above, there is an art that goes along with the science. Different patients will respond differently to the same therapy. In centers where most dialysis takes place, a patient's therapy is honed over time with the aid of staff clinicians or nurses. With home therapy, the patient will visit a clinician's or doctor's office on a regular, e.g., monthly basis, but will not typically have a nurse or clinician at home to help optimize the therapy. For this reason, a mechanism to aid in optimizing a hemodialysis or other blood therapy treatment early on after beginning dialysis is desirable.
Home therapy or HHD also provides the patient with therapy options that the in-center patient does not have. For example, HHD can perform therapy at night if desired, using a single or double needle modality. Any therapy, including a nighttime therapy can be performed over an amount of time that the patient can elect. Because the patient does not have to commute to a center, the patient can perform therapy on days that are convenient for the patient, e.g., weekend days. Similarly, the patient can choose a therapy frequency, or number of therapies per week, that is most convenient and/or most effective. With the added flexibility comes questions, for example, the patient may wonder whether it is better to run six therapies a week at 2.5 hours per therapy or five therapies a week at three hours per therapy. For this additional reason, not only is a way to help optimize a hemodialysis or other blood therapy treatment upfront desirable, it is also desirable to know what will happen when therapy parameters for the optimized therapy are changed.
Optimizing hemodialysis therapies for a hemodialysis patient can also be done by knowing the serum phosphorus levels of the hemodialysis patient during and outside of a hemodialysis treatment session. However, serum phosphorus levels will vary depending on the type of hemodialysis patient and the characteristics of the hemodialysis treatment sessions.
Plasma or serum (the two terms will be used interchangeably) phosphorus kinetics during HD treatments cannot be explained by conventional one or two compartment models. Previous approaches have been limited by assuming that the distribution of phosphorus is confined to classical intracellular and extracellular fluid compartments. More accurate kinetic models able to describe phosphorus kinetics during HD treatments and the post-dialytic rebound period during short HD (“SHD”) and conventional HD (“CHD”) treatment sessions can be used to predict steady state, pre-dialysis serum phosphorus levels in patients treated with HD therapies. This information can be useful in determining optimal treatment regimens for hemodialysis patients.
Hemodialysis therapies can also be optimized by controlling serum potassium levels of a hemodialysis patient during and outside of a hemodialysis treatment session. Plasma or serum potassium kinetics during HD treatments cannot be explained by conventional one or two compartment models. The kinetics of potassium during HD therapies cannot be described using a conventional one-compartment model because the interdialytic decreases in serum potassium concentration are different than those for urea, and there is a substantial post-dialysis rebound of potassium concentration. The kinetics of potassium during HD therapies have been previously described using a two-compartment model assuming that the distribution of potassium is confined to classic intracellular and extracellular fluid compartments with both active and passive transport of potassium between the compartments, but such two-compartment models are complex and require a relatively large number of parameters to describe potassium kinetics. More simple and accurate potassium kinetic models can therefore be useful in determining optimal treatment regimens for hemodialysis patients.